"it"? "#"? ""?

[Matthew Adams]

Hi Remi,

I don't understand what you're trying to say.  Are you saying that instead
of "it", "#" or empty string (implicit closure param), "_" could be used as
an implicit closure param?  If so, then Brian seems to have shot that down
in his last email (no Scala wunderbars).  If not, please explain further.

-matthew

On Sat, Nov 19, 2011 at 3:26 PM, Rémi Forax <forax at univ-mlv.fr> wrote:

> On 11/19/2011 09:45 PM, Brian Goetz wrote:
> > We're pretty satisfied with the degree of syntax reduction we've
> achieved so far.  You can make things arbitrarily compact, but that's not
> the goal.  I don't think that horizontal span is our biggest problem any
> more.  So don't expect any Scala-style wunderbars or Groovy-style it.
>
> and don't forget that even if
>
>   root.listFiles(it.lastModified()<= before);
>
>
> is not legal, this snippet is legal because '_' is a legal identifier
>
>   root.listFiles(_ ->  _.lastModified()<= before);
>
>
> Rémi
>
> >
> >
> >
> >
> > On Nov 19, 2011, at 3:10 PM, John Nilsson wrote:
> >
> >> Given that the usecase for this is about implicit context i really like
> the
> >> last option of just leaving the space before the period unfilled.
> >>
> >> Similarly it would be nice if it worked for all operators:
> list.filter(>2)
> >>
> >> BR,
> >> John million
> >> Den 19 nov 2011 00:51 skrev "Matthew Adams"<matthew at matthewadams.me>:
> >>
> >>> NB:  I'm searching through the archives on this and didn't see anything
> >>> that directly addressed it.
> >>>
> >>> I just got through the slides at
> >>> http://blogs.oracle.com/briangoetz/entry/slides_from_devoxx_talk_on
> >>> and noticed a nice feature inspired by Groovy that was missing from the
> >>> slide code examples.  I don't know if it's missing from the lambda
> >>> proposal, though -- I can't tell from the slides.
> >>>
> >>> Groovy defaults the name of a single closure argument to "it".  I think
> >>> this would be nice to have in JDK8 lambdas, too.
> >>>
> >>> =====
> >>> // Without "it":
> >>> void expire(File root, long before) {
> >>> ...
> >>> root.listFiles(File p ->  p.lastModified()<= before);
> >>> ...
> >>> }
> >>> =====
> >>> // With "it":
> >>> void expire(File root, long before) {
> >>> ...
> >>> root.listFiles(it.lastModified()<= before);
> >>> ...
> >>> }
> >>> ======
> >>>
> >>> Is this possible to include, or will the grammar require "->" so that
> >>> "it.lastModified<= before" isn't interpreted by the compiler as a
> boolean
> >>> expression?  If that's the case, how about considering "#" (or some
> other
> >>> appropriate character) instead of "it"?  That way, the compiler would
> know
> >>> implicitly that if it encounters a "#", it *must* be a lambda
> expression
> >>> taking a single variable of an inferred type:
> >>>
> >>> =====
> >>> // With "#":
> >>> void expire(File root, long before) {
> >>> ...
> >>> root.listFiles(#.lastModified()<= before);
> >>> ...
> >>> }
> >>> ======
> >>>
> >>> You could even reduce "it" or "#" to an empty string and just use the
> "."
> >>> with no preceding scope.  I don't know if the grammar could support
> it, but
> >>> it's interesting.  I'm not sure I like it, but is sure is compact!
> >>>
> >>> =====
> >>> // With "":
> >>> void expire(File root, long before) {
> >>> ...
> >>> root.listFiles(.lastModified()<= before);
> >>> ...
> >>> }
> >>> ======
> >>>
> >>> Another example:
> >>> =====
> >>> // explicit lambda param name
> >>> Set<Album>  favs = albums
> >>>    .filter(a ->  a.tracks.anyMatch(t ->  (t.rating>= 4)))
> >>>    .into(new HashSet<>());
> >>> =====
> >>> // "it"
> >>> Set<Album>  favs = albums
> >>>    .filter(it.tracks.anyMatch(it.rating>= 4)) // 2 its!?!?
> >>>    .into(new HashSet<>());
> >>> =====
> >>> // "#"
> >>> Set<Album>  favs = albums
> >>>    .filter(#.tracks.anyMatch(#.rating>= 4))
> >>>    .into(new HashSet<>());
> >>> =====
> >>> // ""
> >>> Set<Album>  favs = albums
> >>>    .filter(.tracks.anyMatch(.rating>= 4))
> >>>    .into(new HashSet<>());
> >>> =====
> >>>
> >>> Thoughts?
> >>>
> >>> -matthew
> >>>
> >>> --
> >>> @matthewadams12
> >>> mailto:matthew at matthewadams.me
> >>> skype:matthewadams12
> >>> yahoo:matthewadams
> >>> aol:matthewadams12
> >>> google-talk:matthewadams12 at gmail.com
> >>> msn:matthew at matthewadams.me
> >>> http://matthewadams.me
> >>> http://www.linkedin.com/in/matthewadams
> >>>
> >>>
> >
>
>
>


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